Sulfur-liquid hydrocarbon slurries

ABSTRACT

THE INVENTION RELATES TO AN IMPROVED AND NOVEL PROCESS OF PREVENTING SULFUR AGGLOMERATION, STICKING, DEPOSITION AND PLUGGING OF PIPELINES OF PIPELINES TRANSPORTING SULFUR IN THE OF A SULFUR-LIQUID HYDROCARBON SLURRY BY ADDING THERETO AN ANTI-AGGLOMERATE SELECTED FROM NH3 AND H2S.

United States Patent Office 3,745,124 SULFUR-LIQUID HYDROCARBON SLURRIESCharles M. Gable, Lafayette, and Ernest R. Freitas, Orinda, Calif.,assignors to Shell Oil Company, New York, N.Y.

N Drawing. Original application Apr. 28, 1969, Ser. No. 820,012, nowPatent No. 3,606,483. Divided and this application Apr. 23, 1971, Ser.No. 137,058

Int. Cl. B01j 13/00; B27k US. Cl. 252-309 7 Claims ABSTRACT OF THEDISCLOSURE The invention relates to an improved and novel process ofpreventing sulfur agglomeration, sticking, deposition and plugging ofpipelines transporting sulfur in the form of a sulfur-liquid hydrocarbonslurry by adding thereto an anti-agglomerate selected from NH and H 8.

CROSS-REFERENCE This is a divisional application Ser. No. 820,012, filedApr. 28, 1969, now U.S. Pat. No. 3,606,483.

BACKGROUND UP THE INVENTION The transportation of sulfur neat or as awater or oil slurry in pipelines is well known in the art as noted byreference to US. Pats. 2,798,772; 2,917,345 or 2,947,578 or as describedin Pipeline Industry, June 1967, pp. 58- 60. In making the sulfur into asulfur-hydrocarbon slurry, the sulfur is generally sprayed in moltenform into either water or a hydrocarbon to form a slurry suitable fortransportation through a pipeline. Formation of a stable slurry whereinthe sulfur does not undergo any undesirable change or the slurry doesnot exhibit a tendency to wide variation in viscosity is essential tothe process in addition to other problems which may be encounteredduring and after transportation of the slurry through a pipeline. Thus,agglomeration and separation of the sulfur from the carrier fluid,plating, depositing or coating of the sulfur on pipeline walls causingplugging of the pipeline, corrosion, viscosity changes due to pressureand temperature variations requiring great pumping power which increasesoperation costs, etc., are only a few of the problems normallyencountered in transporting sulfurliquid hydrocarbon slurries throughpipelines.

Although the above are serious problems for consideration intransporting sulfur through pipelines, nevertheless the transportationof sulfur in slurry from through pipelines can be made to be effective,attractive and economic means of sulfur transportation, particularlysince sulfur is recovered or obtained from isolated, remote andinaccessible areas, and must be transported to desired accessible areas.As noted above, a number of methods have been proposed for pipelinetransportation of sulfur slurries such as injecting molten sulfur intowater or a liquid hydrocarbon thereby forming a sulfur slurry forpipeline transportation. These methods for making sulfur slurriessuitable for transporting through pipelines generally do not overcomethe agglomeration, deposition, sticking, coating and/ or pluggingproblems described above.

An object of the present invention is to transport sulfur as asulfur-liquid hydrocarbon slurry through pipelines which is stable andflowable.

Still another object of the present invention is to trans port through apipeline sulfur-liquid hydrocarbon slurries without causing sulfuragglomeration, coating, deposition or plugging of the pipeline. 7

Still another object of this invention is to form a slurry of sulfur ina liquid hydrocarbon medium, which does not tend to cause sticking,agglomeration or pipeline plugging or cause any difliculty incirculation of the slurry 3,745,124 Patented July 10, 1973 when saidslurry is pumped and transported through a pipeline and from which thesulfur can be readily recovered at the terminal end of the pipeline asessentially pure sulfur.

Another object is to transport sulfur as a liquid hydrocarbon slurry bypipeline over great distances under conditions of reduced pumping andhandling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to animproved, novel and new technique for transporting a slurry of asulfurliquid hydrocarbon through pipelines over great distances withoutcausing sulfur agglomeration or sticking or sulfur deposition on thewalls of the pipelines due to the tendency of sulfur under suchconditions to adhere to the pipeline Walls because of temperature,pressure and other variable conditions so as to plug said lines; byforming a nonagglomerating sulfur-liquid hydrocarbon for transportationby injecting liquid sulfur into a liquid hydrocarbon containing a sulfuranti-agglomerating agent, preferably one capable of forming freeradicals and optionally having also an effect of lowering the freezingpoint of sulfur so that major portions of the sulfur particles are inessentially S ring form and the liquid hydrocarbon into which the liquidsulfur is sprayed is kept relatively cold. The liquid hydrocarbon canrange in viscosity from a gasoline to a heavy lube oil fraction such asgasoline, kerosene, fuel oil, lubricating oil or crude oil, andfractions and mixtures thereof. The anti-agglomerating agents can bealso added to the sulfur or to both sulfur and the liquid carrier inamounts ranging from 0.1% to over 50% and in the case of gaseousmaterial until saturation of the liquid hydrocarbon is achieved andincludes such materials as halogens e.g. chlorine gas, iodine, hydrogensulfide, hydrogen persul-fides and polysulfides, ammonia and othermaterials which react to form free radicals. The anti-agglomerants canbe injected or admixed with the liquid hydrocarbon or with the liquidsulfur used to make the slurry. The antiagglomerants agent can be addedto the liquid or molten sulfur or to the liquid petroleum as describedor it can be injected when necessary in various places along the pipeline carrying the slurry where indications arethat sulfur agglomeration,deposition, sticking or plugging of the line is taking place. Anyplugging detection means known in the art can be used for this purpose.Thus it has been found that by adding or injecting into a slurry ofsulfur and liquid an anti-agglomerant e.g. NH or H 8 or H S-x wherex=3-6, in which the sulfur content of the slurry can vary from about 10%to about by weight or higher, preferably between 30 and 60% by weightsulfur, that not only does the presence of these materials preventplugging, agglomeration, sticking and deposition of pipelinestransporting said slurry of sulfur on the walls of the pipelines butalso improves the flow of the slurry and reduces pumping costs.

During the preparation of the sulfur-oil slurry improvement additivesother than the anti-agglomerants described above can be introduced inamounts from 0.1% to 10% in order to aid in formation of sphericalsulfur particles generally within the range of l to 800 and preferablybetween 20 and 300 microns and which impart to the slurry otheradditional benefits. The additives best suited for this purpose includeasphaltenic additives which can be 0b tained from unrefined or refinedcrude oil and fractions thereof. By unrefined crude oil is meant anycrude oil which has not been processed in a refinery. Thus, a crude 011may be used as it is removed from the ground, or it may be firstprocessed in field units such as oil-water separators, degasers, etc.Although just how the asphaltenes function in the slurry mixture is notunderstood, it

has been found that the asphaltenes prevent sulfur agglomeration,sticking and aid in the formation of spherical sulfur particles havingdimensions of from 1 to 800 microns and preferably between 20 and 350microns.

The asphaltenes can be recovered from petroleum stocks by any suitablemeans such as described in the Journal of the Institute of Petroleum,February 1.968, pp. 50-53 and April 1968, pp. 107-117, or as describedin U.S. Pats. 3,206,388; 3,288,870; 3,153,623; 2,729,589; 3,368,876;3,364,138; 3,206,388 and 3,275,076. The latter two base materials can beused per se as the asphaltene additive and carrier for the slurry. Inother words, high asphaltenic crudes or fractions thereof containing atleast 1% asphaltenes can be used both as the carrier and additive forthe sulfur slurry. The asphaltenes, asphaltogenic acids and carboids andtheir method of recovery and separation from crudes and fractionsthereof is also fully described in Chapter 9 of Sachanens book on TheChemical Constituents of Petroleum and includes petroleum resins,asphaltenes, asphaltogenic acids and their derivatives. Also, theasphaltenic materials described in U.S. Pat. 2,274,076; 3,284,340 or3,336,146 can be used and they can be separated from petroleum bymethods described in U.S. Pats. 3,364,138 and 3,368,876.

Instead of asphaltenes, natural surfactant components present in crudeoil can be used. The natural surfactants present in crude oil includethe natural polar-containing constituents present in crude oil such asthe nitrogen-, oxygenand sulfur-containing materials can be added to theslurry of sulfur and liquid petroleum as described prior to or duringthe making of the slurry or these active surfactant materials can beinjected when necessary in various places along the pipeline.

The sulfur-liquid hydrocarbon slurry can be made by any suitable means.It is preferred that in the making of the sulfur-liquid hydrocarbonslurry that the conditions of preparation be controlled so that thesulfur in the slurry is present in particle size 340-350 microns and isin spherical form since sulfur in this form in the slurry is moreresistant to agglomeration, attrition and frictional forces.

A method for making the sulfur slurry is described in copendingapplication, Ser. No. 663,755, filed Aug. 8, 1967, which matured as U.S.3,443,837, namely forming a sulfur-aqueous liquid (water) slurry andthereafter phase transferring the sulfur particles from the aqueousliquid into a liquid hydrocarbon containing the antiagglomerants e.g. NHor H 8. The sulfur may be phase transferred directly into a liquidhydrocarbon such as crude oil. Thereafter, the anti-agglomerant can beadded as desired.

PREFERRED EMBODIMENT OF THE INVENTION (1) A 40-60% by weightsulfur-aromatic (17%) enriched kerosene slurry was prepared by phasetransfer by first injecting molten sulfur into an aqueous liquid such aswater and thereafter contacting the slurry thus formed with the aromaticenriched kerosene saturated with H S to effect phase transfer of thesulfur particles into the aromatic enriched kerosene. To the sulfur H 3saturated kerosene slurry was added from about 1% to about 2% ofasphaltenes and thereafter this slurry was injected into a pipeline fortransportation to a terminal station. Sulfur-H 5 saturated keroseneslurries containing option ally a small amount of asphaltenes do notform agglomerates or cause plugging of the pipeline.

(II) An advantage of the present process for transporting throughpipelines sulfur-liquid petroleum slurries as defined is that the slurrycan be also prepared by direct injection of molten sulfur into asuitable petroleum fraction such as kerosene, fuel oil, oil condensateor distillate and mixtures thereof which contains H S or NH and to whichhas been added a small amount of asphaltenes so as to aid in makingspherical sulfur particles and prevent sulfur agglomeration, depositionand plugging of pipelines. Either process as well as other processes canbe used to make the sulfur-liquid petroleum fraction slurry depending onthe availability of the carrier. Thus, where water is available thefirst process can be used and if not the second one can be used.

The presence of the anti-agglomerants during the preparation of thefinal slurry by method (I) or (II) has an additional advantage in thatthe crude oil aids in the formation of spherical surfur particles whichare most desirable since spherical sulfur particles in slurries asdefined provide optimum pipeline performance such as low pressure dropsduring its transportation and ease of recovery and purification at theterminal end of the pipeline.

The following examples illustrate the essence of the present invention.

(A) Molten sulfur at l20-l60 C. was sprayed into aromatic (17%) enrichedkerosene through a spray nozzle at about 200 psi. pressure drop to givea homogeneous slurry with sulfur solids content of about 16% by volumein which the sulfur particles were essentially large angular-crystallineparticles which began to stick together and agglomerate into a stickymass within about 10-15 minutes.

(B) The method of (A) was repeated except that H S was added to thekerosene carrier. The particles formed were microspherical (20-450microns) in shape and no tendency of the particles to stick oragglomerate were noted.

In another test different petroleum fractions were used to form sulfurslurries Where in a 90-ml. portion of molten sulfur at 140 C. wasinjected as a continuous stream for 0.5 minute into a Well-stirred 500ml. charge of a petroleum carrier. As shown in Table 1 some of thecarriers were used neat and to some were added H 8 or NH For comparisonvarious surfactants were added to sulfur-oil slurries and the resultsare shown in Table 1.

TABLE 1.EFFEC'I OF ADDITIVES ON SULFUR DISPERSION Conditions: 500 ml.carrier in l-liter Morton flask. 90 ml. sulfur at approximately 140 0.added 0.5 minute. 1,200 r.p.m. with crescent blade stirrer CoagulumMajor fractions, per- Imtial Level, (+12 mesh), cent weight basis slurrytemp., percent percent weight Particle Run Carrier 0 weight Type basis Sfed 16, +30 30, +50 (15011. shape a 1 Petroelum fraction (Water- 22 None19. 1 57. 7 19. 3 680 A ton condensate) 2 do 22 1 Bryton 430 (62%alkylaryl 20.4 60.0 21.0 710 A sulfonate) 24 1 Oleic acid 30 72. 0 13. 7770 A 23 1 Naphthenic acid bottoms.-. 30 A 23 1 Dehydroabietic acid 30 A21 1 50% dodecyltrimethyl- 13. 8 62. 6 20.8 700 A. ammonium chloride. 736% kerosene/white 011 23 (d) N 113 7.0 64. 6 24. 0 690 S (Watertoncondensate). 8 Crude O11 23 ((1) Has 5 60. 5 20. 5 500 e S=spherical,A=agglomerated, in estimated order of abundance in +30 mesh fraction.

uns.

600 r.p.m. in early scouting runs and in all C. r

e Derived from Canadian oil field. API gravity=54.9; viscosity, cs. 59F.=0.953 and 77 F.=0.865 flash oint, ta 0 en cu F.=7; u F.=80; sulfur,percent weight t0ta1=1.14; FIA, percent weight saturates=82 andaromatics=18. p g p m I point d Saturated.

Sulfur slurries of the present invention containing antiagglomerants,e.g., H S or NH can be transported through pipelines over greatdistances without the danger of sulfur deposition, agglomeration,sticking or plugging of the pipelines.

At the terminal end of the line the sulfur can be removed from theliquid hydrocarbon by suitable means such as described in US. Pat.2,798,772 and the sulfur purified by methods as described in US. Pat.2,809,885 or as described in the copending patent application Ser. No.684,507, filed Nov. 20, 1967 now Pat. No. 3,489,667 which comprisestreating oil contaminated sulfur with an aqueous solution containing amixture of alkali hydrosulfide and corresponding hydroxide, e.g.,ammonium hydrosulfide and ammonium hydroxide, or by other suitable meanssuch as sulfur can be recovered from the oil slurry by filtration ofmolten sulfur and liquid-liquid extraction with a hydrocarbon solventcontaining 50% aromatic. Thus, at the receiving terminal the sulfurslurry can be filtered and Washed. The recovered sulfur is then meltedand purified by liquid-liquid extraction with an aromatic hydrocarbonsuch as cumene. Also, if desired, the filtered sulfur can be steamstripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to beexplanatory thereof. Various changes in the details of the describedmethod may be made within the scope of the appended claims withoutdeparting from the spirit of the invention.

I claim as my invention:

1. An agglomeration resistant sulfur-hydrocarbon slurry comprising fromabout 10% to about 75% essentially spherical sulfur particles ranging insize from about 1 to about 500 microns in liquid hydrocarbon containingan anti-agglomerate selected from the group consisting of NH and H S.

2. The composition of claim 1 wherein the anti-agglomerate ranges fromabout 0.1% to over of the slurry.

3. The composition of claim 1 wherein the hydrocarbon contains from 0.1%to about 10% asphaltenes.

4. A method for preventing agglomeration in sulfurhydrocarbon slurriescomprising admixing therewith an anti-agglomerate selected from thegroup consisting of NH3 and H28.

5. The method of claim 4 wherein the anti-agglomerate ranges from about01% to over 50% of the slurry.

6. The method of claim 4 wherein the slurry includes from about 0.1% toabout 10% asphaltenes.

7. The method of claim 4 wherein the sulfur is spherical in shape andranges in size from about 1 to about 500 microns.

References Cited UNITED STATES PATENTS 6/1953 Burton et a1. 117--139OTHER REFERENCES JOHN D. WELSH, Primary Examiner U.S. Cl. X.R. 252-481;302-66

